1. Field of the Invention
The present invention relates to apparatuses useful for testing objects using wave energy. More particularly, the present invention relates apparatuses useful for testing tubing using ultrasonic wave energy.
2. Description of the Prior Art
Several types of devices are known in the prior art which are adapted to test tubing using wave energy. Conventional ultrasonic testing of tubing involves a high speed rotation of the tubing, i.e., rotation at approximately 2500 rpm. The disadvantage of an apparatus employing such a method is that a mechanical drive system of such an apparatus is normally plagued both by slippage of the tubing, which drastically reduces the accuracy of the testing, and by low throughput of the tubing through the apparatus, which increases the cost and decreases the efficiency of the testing.
Other testing apparatuses are known which do not involve rotation of a test object, but which do involve the rotation of a set of transducers. For example, U.S. Pat. No. 4,562,738 granted to Nagayama et al. discloses an automatic flaw detection device which includes a supporting frame, a rotational frame which rotates freely inside the supporting frame, and ultrasonic searching units which are mounted on the rotating frame and which probe a material passing through the device, wherein signals are sent to and from the searching units through a rotor section and a stator section. Similarly, a system is known in which multiple transducers are mounted on a large head which rotates at several thousand rpm to test a tube that is not rotating.
The disadvantage of such apparatuses is that the need to electrically connect the rotating transducers to a stationary sensor or memory greatly complicates the design of such apparatuses, as is evident in the Nakayama et al. device, which includes a rotor section and a stator section for rotational-to-stationary electrical connection. The complicated designs of these apparatuses necessarily make them more expensive and more prone to break down.
Still other types of devices which involve non-rotating test objects and stationary transducers are known for testing tubing using wave energy. U.S. Pat. No. 3,121,324 granted to Cowan discloses an ultrasonic inspection apparatus for inspecting cylindrical bars, which includes two stationary transducers and a rotating reflector which directs pulsed ultrasound from one of the transducers through a cylindrical bar onto the other of the transducers. U.S. Pat. No. 4,089,227 granted to Falgari et al. discloses an ultrasonic apparatus for measuring the radial dimensions of a cylindrical tube, which includes two stationary transducers which emit pulsed ultrasound, a rotating disk having two openings through which the pulses pass, and a cone-shaped mirror which reflects the pulses onto the tube and which reflects echoes from the tube back to the transducers through the openings. U.S. Pat. No. 4,361,044 granted to Kupperman et al. discloses a scanning ultrasonic probe assembly which fits inside a tube to make various geometric measurements of the tube, wherein the assembly includes two non-rotating transducer assemblies, and two rotating mirrors which reflect ultrasonic signals from the transducer assemblies onto the tube, and from the tube back to the transducer assemblies.
These types of apparatuses have the disadvantage, however, that they are able to perform only a single type of test on a test object, and/or that they are still fairly complicated in design.
U.S. Pat. No. 4,580,451 granted to Miwa et al. discloses an ultrasonic sector-scan probe for observing living tissue, which includes a linear array of ultrasonic transducer segments arrayed on a circular arc, and a window which includes a converging lens or a diverging lens to focus on ultrasound beam from the liner array onto the living tissue. However, the probe of the Miwa et al. patent is only usable for one stationary sector scan at a time, and thus is limited in usefulness for applications where large portions or lengths of tubing need to be tested rapidly.